Committed this morning to David Airlie's DRM testing repository is the initial CS (Command Submission) parser for the Evergreen (also referred to as the "R800" series) ASICs. This allows commands needed for 3D acceleration to be submitted to the GPU. The noteworthy part, however, is part of the commit message that reads: "The mesa code that uses this will be released soon."
The commit that adds the Evergreen command submission parser can be found on the CGit page. It's good to see the initial Mesa code for the ATI Radeon HD 5000 series graphics processors finally coming, but it will likely be initially published in the form of a classic Mesa DRI driver before it will appear in the form of a Gallium3D driver. Though this is a matter that has been previously talked about with regards to 3D support on Evergreen.
Ideally this initial Mesa 3D support will be merged prior to the Mesa 7.9 branching this summer. However, with the needed Radeon DRM changes not yet being in the mainline Linux kernel for the Linux 2.6.35 kernel, this may not make it supported until the Linux 2.6.36 kernel rolls out, which would put it out of reach for Ubuntu 10.10, unless it were to be back-ported by Canonical and other distribution vendors.